Power regeneration system for chopper circuits

ABSTRACT

The conventional use of an electromechanical switching device in a DC-DC chopping circuit is avoided by a chopper circuit including a main switching device and first and second auxiliary switching devices for controlling the main switching device and for providing charging and discharging paths for the commutation capacitor.

United States Patent 3,594,629 [72] inventors Chuji Kawakami; [50] Field of Search 321/2, 43, lchiro Kouzuma, both of Tokyo, Japan 44, 45, 45 C, 45 ER; 307/240. 255; 323/22 SC, 18; [21] AppLNo. 881,517 318/341,345

[22] Filed Dec. 2, 1969 I j 45 Patented July 20,1971 1 1 References CIM [7 3] Assignee Kahushiki Keisha Meidensha UNITED STATES PATENTS Tokyo/hp 3 303 416 2/1967 Paice et al. 323/22 132! Pmmy 3,372,327 3/1968 Morgan 321144 x [331 3,372,329 3/1968 Steimel etaL. 321/45 x 43/911438 3,396,293 8/1968 Harris 321/2 ux 3,517,290 6/1970 Gunsser 318/341 X Primary Examiner-Wi1liam H. Beha, Jr. 541 PowER REGENERATION SYSTEM FOR CHOPPER and Herman CIRCUITS M 5 cmms4nnwmg ABSTRACT: The conventional use of an electromechanical [52] US. Cl 321/2, switching device in a DC-DC chopping circuit is avoided by a 318/341, 318/345, 321/44, 321/45 C, 323/18, chopper circuit including a main switching device and first 323/22 SC and second auxiliary-switching devices for controlling the [51] Int. Cl ..ll02m 3132, main switching device and for providing charging and discharging paths for the commutation capacitor.

fswitch es.

' service life.

I "gy from the load.

' .power from a direct current source to a load do not permit power to be retumed directly from the load to the source because of the circuitry required to provide the power adjust 1 ing feature. Thus, itzhas been necessary heretofore to connect such'a chopper circuit with a second circuit which provides the necessaryipower return. The knowuarrangement has required the usef of electromechanical switches having movable contacts. for connecting and disconnecting the chopper circuit and the return circuit. Because of contact wear, the

performance of. such arrangements is poor, and their service lift is-short. Y

his the primary object of this invention to provide a chopper circuit includinga return circuit which permits the switching'of power-supplied from-a direct current source to a load. and power return from the load to the source, by electronic switching means without the useof electromechanical Another object-of the invention is theprovision of a chopper circuit which has no mechanical'contacts, and which isireliable in performance; is easy to operate, and hasa long Additional objects, features, and advantages of this invention will'becorne evident from the following description of a preferred embodiment when. considered in conjunction with theacconipanying drawing in which FIG. IA is a diagram of a knowncircuit for supplying power from a di'rect-current source to a load; I FIG. .IBsimilarly shows a l nown circuit for returning power fromlthe load to the source; s FIG. .IC illustratesa known circuit for supply and power return; and v A I FIG. 2 is a circuit diagram of a chopper circuit according to providing both power this invention.

'The'chopper circuit of the priorart illustrated in FIG ..1A supplies powerof any desired value'from a direct-current power. source l'anda-rnain thyristor 2 to a load 9 which may Y be an electric motor. The circuit further includes anauxiliary thyristor '3 which aids in turning the main thyristor2 on and off,and a commutation capacitor 4 for inversely biasingthe I thyristor 2, 3 by thecharge voltage developed across the capacitor to turn the thyristors off. A commutation reactor 5 fonns a resonant circuit with a capacitor 4. A commutation and .to a direct-current reactor8 .for temporarily storing ener- The circuit shown in FIG. IA operates as follows: When the auxiliary thyristor Sis turned on by agate control and load 9 so that the anode side of the main thyristor 2 becomes positive. When the latter is turned on by the nonilluscapacitor 4 is discharged through the auxiliary thyristor 3, reactor 8, and load 9. During discharge of the capacitor 4, the main thyristor 2 is inversely biased and turned off by the charge voltage of the capacitor 4, whereby power to the load 9 is shut ofi. After being discharged, the capacitor 4 is recharged from the power source I through a path including the capacitor 4, the auxiliary thyrist0r3 'thereactor 8, and "the load 9 in such a manner that the anodeside of the thyristor 2 becomes positive, whereupon another cycle rnay start.

It is imposible to return power directly from the load 9 to the power source I in the circuit of FIG. 1A. It has been common practice prior to this invention to connect the power source 1 to a circuit as shown in FIG. 1B for effective power return. Inthis circuit, the main thyristor 2 is turned on by the 'gate control circuit so that the power of the load 9 is accumulated infthe direct-current reactor 8 from which. it is returned to the power source I through the smoothing diode 7 when the .:main thyristor 2 is turned off.

To combine the features of the circuits of FIGS. IA and IB, as is shown' in FIG. IC, the known system requires mechani cally operated switches, such as the illustrated doubie'throw switches 10 or corresponding relay contacts, for disconnecting thyristor 3a is connected'to the positive terminal of the power source in a .secondseries circuit with a second commutation reactor 5b. A first commutation diode 6a isconnected parallel tothe main thyristor 2 with opposite polarity. A commutation capacitor. 4 connects the ends of the two series circuits remote from the current source I. i

v A second commutation diode 6b and a power return thyristor I] are arranged in parallel circuit with opposite diode 7 aids in turning the'thyristors off. A smoothing diode 7 Q reduces 'the fluctuations of the current passed to the load 9 polarity, and in a'second series circuit witha third commutation reactor 5c which connects the anode of the diode 6 h to the negative terminal of the power source I. The other end .of the parallel circuit 67:, -11 is connected to the juncture of the capacitor 4 and the main thyristor 2 of the first series circuit. A thirdseries circuit of ,a second auxiliary thyristor 3b and a fourth commutation reactor 5d connect the negative terminal of the power source l to thejun'ctureof the capacitor 4 with the auxiliary thyristor '30. The two terminals of the load 9 are connectedrespectively to thei negative terminal of the power source I and, through a direct-i'current reactor 8, to the juncture of the capacitor-4 with the first and second series circuits. The circuit of FIG. 2 is operated as follows:

, when poweris supplied form the source I to the load 9, the main thyristor 2is turnedon and-off without turning the power return thyristor 11 on. Wheri the main thyristor 2 andthe second auxiliary thyristor 3b are simultaneously turned on by the gate control circuit .(not shown), current passes from the source I .to the load 9 through 'the reactor 50, main thyristor '2,

and reactor 8. At the same time, .the capacitor 4 :is charged a current supplied .by the source .1 through acircu-it which includes the'reactor 50, main thyristor 2, capacitor 4, thyristor 3b, and .reactor 5!: in .such a manner that the cathode side .of

trated gate control circuit, the capacitor 4 isdiseharged through the main thyristor 2, reactor 5, and diode fissimultaneously with the supply of power form the source Ito the load 9 through the reactor 8. As soon as the capacitor 4 is discharged, the capacitor is recharged in such a'manner that I the anode side of the auxiliary thyristor becomes positive. The

recharging voltage is higher than the previous charging volt- .age,.and-the auxiliary thyristor 3 is inversely biased and turned .off bya transientvoltage which is produced by resonance of the capacitor 4 and the reactor S during the recharging period I of the capacitor. when the auxiliary thyristor 3 is turned on thereafter by the nonillustrated. gate control circuit, the

' the .main thyristor 2 becomes positive. The second auxiliary thyristor 3bis turned off when'thedirection of current flowris reversed .by the resonance of the capacitor .4 and the reactors Saand 5d respectively.

When the :first auxiliary thyristor 3a is turned on thereafter I by the gate control-circuit (not shown), the capacitor 4 is discharged through acircuit including the diode 6a, the reactors 5a and 5b, and the auxiliary thyristor 30. When the capacitor charge is dissipated,-t'he capacitor 4 is recharged .in such a manncr'that thecathodeside of the thyristor 30 becomes positive. The recharge voltage of the capacitor 4 is higher than the voltage of the previous charge. The main thyristor2 isinversely biased during the recharging and turned commutation diode with its anode capacitor 4 and the reactorsSa, 5h. The auxiliarythyristor 3a "is inversely biased by the high recharge voltage of the capacitor 4 and turned offwhen recharging of the capacitor is ,completed. When'the second auxiliary thyristor B is turned von thereafter by thegate control circuit (not shown), the

charge on the apacjtor 4 is dissipated througha circuit which includes thethyris'tor. 3b, the reactors 521,52", and the diode 6b.

After dissip ation of the charge, the capacitor 4 is recharged in t .such a manner that the cathode side of the thyristor 2 becomes positive. The thyristor 3B is turned off by the resonance of the capacitor 4 and of the reactors 5d, 50 when the direction of t f current flow is reversed. f'

The cycle repeated afterthe main thyristor 2 andauxiliary thyristor Share" turned on by the nonillustrated gate control circuit. Direct current ofa desired value is thus supplied to the load 9 by; turning the thyristor 2 on and off in a controlled I manner.

such a manner that the cathode side of the thyristor 3a becomes positive, the'power of the'load'9 is stored in the direct current reactor 8. At the same time, the capacitor 4 is discharged through the thyristor 3b, the reactors 5d, 50 and the diode 6b, and the power return thyristor 11 is inversely biased and turned off by a transient voltage produced by the resonance of the-capacitor 4 and the reactors 5c, 5d. The

off bya transient voltageproduced by resonance of the of said first auxiliary thyristor, .a fourth commutation reactor connected between the cathode of said second auxiliary thyristor and the negative side of said direct-current voltage and forming a third series circuit with ,said second auxiliary thyristor, said third series circuit being connected between said at least-one commutation capacitor-and the negative side ofsaid direct-current voltage. 1 w

2. In a chopper circuit for supplying a variable amount of power from a direct current source to aload, said chopper circuit including a main switching device for supplying a controllable amount of power from said source to said load; a first auxiliary switching device connected across said .main

switching device to aid the switching thereof; afirst commutation reactor; a commutation capacitor connected to said main and said first auxiliary switching devices; and a commutation diode connected across said rnain switching device, said first commutation reactor and said commutation capacitor forming a first portion of a first resonant circuit. across said main switching device to switch said main switching device; a direct-current reactor serially connected with said load; a smoothing diode connected across said load and Said directcurrent reactor; and switching means for reversing the ter minalsof said smoothing 'diode to return power stored in said direct-current reactor to said source'when said main switching device is nonconducting, the-improvement whichcotnprises:

thyristor 3b is turned off when the current flow is reversed, as

described above. The power stored in the reactor 8 is returned to thesourcel throughthe diode6a when the thyristor I1 is turned ofi'.

-The power return system of the invention thus permits "power return from the load to the power source in a single circuitlwithout switching from. one circuit to the other. Thyristors are employedandswitched electronically without the use of mechanicIal 'sviitchesThe chopper circuit has a long service life, and'is positive in its operation. The commutation capacitor is charged and'dischargedwitho'ut the passage of charging current through the load so that the circuit may be operated without a connected load. The voltage rise resulting from turning the thyristors on and off in the specifically illustrated embodiment isreduced by the division of the commutation reactor into four elements.

We claim: I I 1. A power regeneration system for chopper circuits comprising at least one main thyristor with its anode being disposed on the positive side of a direct-current voltage,,a first commutation reactor forming a first series circuit with at least one main thyristor, a;first auxiliary thyristor with its anode being disposed onth'e positive side of said direct current voltage,ia second commutation reactor forming a second series circ'uitwith said firstau'xiliary thyristor, one end of each of saidfirst and secondseries-circuits being connected to the positive side of said direct current voltage, a first commutation diode connected in parallel with said at least one main thyristor in such a manner that their polarity is reversed, at least one commutation capacitor connected between the other ends of said first and second eries circuits, a second disposed on the negative. side of said direct current voltage, at leastone power regeneration thyristor connected to said second commutation diode to forma parallel circuit therewith in such a manner that their polarity is'r'eversed, a third commutation reactor ommu'tation capacitor onthe .main

. thyristor side, asecond"auxiliary thyristor with its cathode end being connected "to the negative side of said direct-current voltage and its anode and beingctinri'ected to the juncture of said at least one commutation capacitor and the cathode end fc'uit which is also connected to one 3. The chopper circuit according to claim 2', wherein said first commutation reactor is serially connected with said main switching device, and said switching means comprises a. a secondcommutation reactor. serially connected with said first auxiliary switching vdevice and forming a second portion of saidfirst resonant circuit with said commutation capacitor across said main switching device; and b. a third commutation reactor serially connected with a. powerreturn device and fonning a first portion of a second resonant circuit with said com'mutation capacitor across'said load and said direct-current reactor, said second portion of the first resonant circuit effecting, with said first portion of the first resonant circuit, switching of said main device, and saidsecond resonant'circuit effecting switching ofsaid second auxiliary switching device.

4. The chopper circuit according to claim-3 further'com prising-a fourth commutation reactor serially cpnnected with said second auxiliary switching device and forming a second portion of said second resonant circuit across said main switching device, said first and second portions of said second resonant circuit together effecting switching of said second auxiliary device. I

5. A chopper circuit for supplying a variable amount of power from a direct-current source to a load, which comprises: Y I I I a. a main switching device connected between said direct current source and said load to supply said powerj b. an oppositely p'oled first commutation diode connected in parallel across said main device to aid the switching thereof; Y Y c. a first commutation reactor serially connected with the parallel connection of said main device and said first commutation diode; g v. d. a direct-current reactor serially connected to said load to store energy when said main switching device is nonconducting; y a commutation capacitor connectedat one end of the juncture of said main switching device and said directcurrent reactor and forming with said first commutation reactor a first portion of a resonant circuit to switch said main device; a first auxiliary switching device serially connected, ith a second commutation reactor between the other end of k. a second auxiliary switching device connected between the juncture of said commutation capacitor and said first auxiliary switching device and said source to provide a charging path for said commutation capacitor; and

l. a fourth commutation reactor serially connected with said second auxiliary switching device and forming a second portion of said second resonant circuit with said commutation capacitor, said first and second portions of said second resonant circuit cooperating to effect switching of said second auxiliary switching device. 

1. A power regeneration system for chopper circuits comprising at least one main thyristor with its anode being disposed on the positive side of a direct-current voltage, a first commutation reactor forming a first series circuit with at least one main thyristor, a first auxiliary thyristor with its anode being disposed on the positive side of said direct current voltage, a second commutation reactor forming a second series circuit with said first auxiliary thyristor, one end of each of said first and second series circuits being connected to the positive side of said direct-current voltage, a first commutation diode connected in parallel with said at least one main thyristor in such a manner that their polarity is reversed, at least one commutation capacitor connected between the other ends of said first and second series circuits, a second commutation diode with its anode being disposed on the negative side of said direct current voltage, at least one power regeneration thyristor connected to said second commutation diode to form a parallel circuit therewith in such a manner that their polarity is reversed, a third commutation reactor disposed between the negative side of said direct-current voltage and said parallel circuit which is also connected to one end of said at least one commutation capacitor on the main thyristor side, a second auxiliary thyristor with its cathode end being connected to the negative side of said direct-current voltage and its anode end being connected to the juncture of said at least one commutation capacitor and the cathode end of said first auxiliary thyristor, a fourth commutation reactor connected between the cathode of said second auxiliary thyristor and the negative side of said direct-current voltage and forming a third series circuit with said second auxiliary thyristor, said third series circuit being connected between said at least one commutation capacitor and the negative side of said direct-current voltage.
 2. In a chopper circuit for supplying a variable amount of power from a direct current source to a load, said chopper circuit including a main switching device for supplying a controllable amount of power from said source to said load; a first auxiliary switching device connected across said main switching device to aid the switching thereof; a first commutation reactor; a commutation capacitor connected to said main and said first auxiliary switching devices; and a commutation diode connected across said main switching device, said first commutation reactor and said commutation capacitor forming a first portion of a first resonant circuit across said main switching device to switch said main switching device; a direct-current reactor serially connected with said load; a smoothing diode connected across said load and said direct-current reactor; and switching means for reversing the terminals of said smoothing diode to return power stored in said direct-current reactor to said source when said main switching device is nonconducting, the improvement which comprises: a second auxiliary switching device connected between said first auxiliary switching device and said direct current source to discharge said commutation capacitor when both said main and said first auxiliary switching devices are nonconducting.
 3. The chopper circuit according to claim 2, wherein said first commutation reactor is serially connected with said main switching device, and said switching means comprises a. a second commutation reactor serially connected with said first auxiliary switching device and forming a second portion of said first resonant circuit with said commutation capacitor across said main switching device; and b. a third commutation reactor serially connected with a power return device and forming a first portion of a second resonant circuit with said commutation capacitor across said load and said direct-current reactor, said second portion of the first resonant circuit effecting, with said first portion of the first resonant circuit, switching of said main device, and said second resonant circuit effecting switching of said second auxiliary switching device.
 4. The chopper circuit according to claim 3 further comprising a fourth commutation reactor serially connected with said second auxiliary switching device and forming a second portion of said second resonant circuit across said main switching device, said first and second portions of said second resonant circuit together effecting switching of said second auxiliary device.
 5. A chopper circuit for supplying a variable amount of power from a direct-current source to a load, which comprises: a. a main switching device connected between said direct current source and said load to supply said power; b. an oppositely poled first commutation diode connected in parallel across said main device to aid the switching thereof; c. a first commutation reactor serially connected with the parallel connection of said main device and said first commutation diode; d. a direct-current reactor serially connected to said load to store energy when said main switching device is nonconducting; e. a commutation capacitor connected at one end of the juncture of said main switching device and said direct-current reactor and forming with said first commutation reactor a first portion of a resonant circuit to switch said main device; f. a first auxiliary switching device serially connected with a second commutation reactor between the other end of said commutation capacitor and said source, said second commutation reactor forming with said commutation capacitor a second portion of said resonant circuit to switch said main device; g. a power return device connected in parallel across said direct-current reactor and said load; h. an oppositely poled second commutation diode connected in parallel with said power return device to provide a discharge path for said commutation capacitor; i. a third commutation reactor serially connected with said power return device and forming a first portion of a second resonant circuit with said commutation capacitor; k. a second auxiliary switching device connected between the juncture of said commutation capacitor and said first auxiliary switching device and said source to provide a charging path for said commutation capacitor; and l. a fourth commutation reactor serially connected with said second auxiliary switching device and forming a second portion of said second resonant circuit with said commutation capacitor, said first and second portions of said second resonant circuit cooperating to effect switching of said second auxiliary switching device. 